Loading gate assemblies



Aug- 29, 1951 w. GRn-:sr-:LHUBER 2,998,220

LOADING GATE ASSEMBLIES Filed Feb. 28, 1956 5 Sheets-Sheet l d. 0 n BY $2@ PMM ma; ATTORN YS lNvEN-roR lo J WILL/AM CmEsam/BER Aug. 29, 1961 w. GRIESELHUBER LOADING GATE: AssEMBLIEs 5 Sheets-Sheet 2 Filed Feb. 28. 1956 @mwN INVENTOR WILL/AMCR/Ese-Hun Aug- 29, 1961 v w, GRIESELHUBER 2,998,220

LOADING GATE AssEMBLIEs Filed Feb. 28, 1956 3 Sheets-Sheet 3 INVENTO R W/.L/AM GRIESEL Hune BY www ATTOR EYS 2,998,220 LOADING GATE ASSEMBLIES William Greselhuber, Hamilton, Ohio, assignor to The Western States Machine Company, Hamilton, Ohio, a corporation of Utah Filed Feb. 28, 1956, Ser. No. 568,254 11 Claims. (Cl. 251-31) This invention relates to loading gate assemblies, and more particularly to yloading gate assemblies having a novel pressure seating arrangement.

In many industrial processes, it is often desired to control the ow of a substance passing from one processing unit to another. One means of accomplishing this is the use of loading gates, located between the processing units. Loading gates suitable for this use generally comprise a gate body having a passageway extending therethrough which serves to guide the flow of the substance being processed. A closure member is seated on a facing surrounding one end of the passageway and is movable along the facing to open and close the passageway thereby permitting or preventing ilow of the substance. In order to prevent leakage of the substance when the loading gate is in a closed position, it is desirable that the closure member be forced against the facing on the gate body to provide a tight frictional engagement therebetween. However, this presents a serious problem when the closure member is moved to open or close the gate, since the tight frictional engagement between the closure member and facing requires a large operating force to move the closure member.

This problem is of particular importance in the sugar industry where mixtures of sugar crystals and syrup, called sugar massecuite or magma, are handled. In the process of manufacturing or refining sugar, it is necessary to separate the syrup from the aforesaid mixture of sugar crystals and syrup. This is usually accomplished by placing a suitable quantity or charge of the mixture in a sugar centrifugal which performs the actual separating function. Prior to loading the mixture into the centrifugal, it is stored in a mixer tank which holds enough charge material lio-r several of the centrifugal machines. In order to Aguide and control the ow of the mixture into the centrifugals from the mixer tank, a loading spout and associated loading gate assembly are normally employed.

A loading gate satisfactory for this purpose must meet difficult operating requirements. The mixture from the mixer tank has a tendency to form hard deposits of sugar crystals on the facing of the gate, thus preventing adequate closure and permitting leakage therefrom. It is important to prevent such leakage, and also to have the gate operate reliably in a definite period of time for each loading operation, and without requiring excessive operating forces. To these ends, a tight frictional engagement is needed between the closure member and the facing when the gate is in a closed position, and a lesser frictional engagement for all other positions of the gate.

It is an object of this invention to provide a loading gate assembly which is particularly suitable 4for use in connection with centrifugal machines and which has its parts arranged in a simple functional organization that is economical to manufacture and requires relatively little space for its installation.

A further object of this invention is the provision of a loading gate assembly which requires no anchors or supports other than the loading spout itself and can accordingly be mounted close to the basket spindle of a centrifugal machine. l

An additional object of this invention is the provision of a loading gate assembly which constitutes an improvemm Over prior art gates as exemplified by that dis- Patented Aug. 29, 1961 closed in United States Patent No. 2,337,817, in that the assembly of the present invention is simpler and more economical to manufacture, and in that it enables the elimination of numerous parts of the prior gates without any sacrifice of desired functions.

As set .forth more particularly hereinafter, the invention is applied to a type of loading `gate in which a gate body forming a passageway for the material to be delivered through the gate is provided with a facing that surrounds one end of the passageway and is extended along the gate body to form a plane bearing surface upon which a closure member is seated. A crosshead mounted for movement relative to the gate body is operably connected to the closure member so that movement of the crosshead moves the closure member along the bearing surface to open and close the passageway.

According to one feature of the invention, an inilatable means which is adapted for connection with a source of fluid pressure is provided between the crosshead and the closure member, the inflatable means having a distendable Wall operative to bear against the closure member and press it against the facing with a force proportionate to the iluid pressure existing in the inflatable means. Fluid supply means are also provided to supply into the inflatable means a fluid under high pressure when the closure member is in closed position and a fluid under reduced pressure when the same is moved from closed position, thereby ensuring a tight frictional engagement between the closure member and the facing when the gate is in a closed position and a lesser frictional engagement for all other positions of the gate.

In one embodiment of the invention, the inflatable means may take the form of a pressure bag constructed of flexible elastic material and wherein a portion of the surface of the bag forms the distendable wall which is operative to bear against the closure member.

ln another embodiment of the invention, the inflatable means may comprise a rigid member forming a cavity and a wall constructed of flexible elastic material sealing the cavity. The wall of exible elastic material bears against the crosshead and the rigid member itself forms the distendable wall which is operative to bear against the closure member.

According to another fea-ture of the invention, a simple functional organization of the operating parts of the loading gate is achieved by the use of fluid pressure responsive means, including at least one pressure cylinder carried by a part of the crosshead and a lxed piston in the cylinder, for moving the crosshead relative to the gate body. This arrangement materially reduces the space required -for installation of the Iloading gate assembly and makes it suitable for use with centrifugal machines and the like.

According to still another feature of the invention, a nid control valve is provided to reversibly control the operation of the uid pressure responsive means to open and close the gate. The fluid control valve when shifted from a gate closed position to a gate open position, also serves to transiently vent the inatable means, thereby cooperating with the fluid supply means to form a simplified integrated control system.

The foregoing and other objects, features and advantages of the invention will become apparent from the following description of illustrative embodiments of the invention when considered in connection with the drawing in which:

FlG. 1 is a side elevation, partially in section, of a loading gate assembly constituting one embodiment of the invention;

FIG. 2 is a front elevation, partially in' section, of the embodiment of FIG. l; l,

FIG. 3 is a horizontal section of the loading gate assembly of FIG. 1 taken along line 3-3 of FIG. 2;

FIG. 4 is a detail view showing elements of construction of a tube connecting block and spring-loaded piston valve employed in the control system for the loading gates;

FIG. 5 is a schematic diagram of a uid pressure operated control system suitable for use with the loading gates of the invention;

FIG. 6 is a side elevation, partially in section, of a loading gate assembly constituting another embodiment of the invention;

FIG. 7 is a front elevation, broken away to reveal certain details of construction of the embodiment of FIG. 6; and

FIG. 8 is a horizontal view, partially in section, of the loading gate assembly of FIG. 6.

Referring first to FIGS. l to 3 of the drawing, there is shown a loading spout 10 which forms part of a mixer tank (not shown). A gate body 11 forming a passageh way 12 is connected to the loading spout 10 by means such as bolts 413, such that the passageway forms a continuation of the loading spout. The gate body 11 s positioned immediately above the curb 14 of a centrifugal machine (not shown). The function of the loading gate described herein is to control and guide the flow of the mixture from the mixer tank to the centrifugal machine. To this end, a closure member or plate 15 is seated on a facing 116 which surrounds the passageway 12 and extends along the gate body 11 to form a bearing surface. The facing 16 may be formed of any hard wear-resistant material such as for example, Stellite, which is an alloy of steel with cobalt, chromium and tungsten.

A crosshead 17 is mounted for movement relative to the gate body 11 in the direction of the facing extension and is connected to the closure member 15 so that the 'closure member will be carried along the facing by movement of the crosshead. As seen in FIG. 3, the connecting means take the form of bolts 19 which threadedly engage the crosshead 17 and extend into sockets 20 located in the closure member 15. For reasons which will become evident, the ends of the bolts -19 are received loosely in the sockets 20 in the direction normal to the plane of the facing 16. The sockets also are sufficiently large that there is a degree of lost motion between the ends of the 'bolts and the sockets in the direction of the facing extension. Thus the crosshead assembly is capable of sliding relative'to the closure member for a limited distance in the direction of theV facing extension.

Slide members 21 and 22 are bolted to the rear portion of the crosshead 17 by a series of bolts 23 and 24 and engage respectively, extended portions 21A and 22A of the Agate body. The extended portions 21A and 22A of the gate body, form guide means which provide bearing surfaces along which the crosshead moves to open and close the gate. Passageways 25 and 26 are formed in the slider members 21 and 22 so that adequate lubrication of the bearing surfaces may be obtained. The crosshead 17 has vertical bores 27 and 2S formed therein at opposite sides of the passageway. Adjacent each of the bores, the crosshead is slit at 29 and 30, and bolts 31 and 312. passed through the slit portions to provide clamping arrangements. The clamping arrangements serve to connected the crosshead with the cylinder portions 33 and 34 of the double-acting presure cylinder means 35 and 36.

The doubleeacting pressure cylinder means 35 and 36 also include fixed pistons 3,7 and 38 which are supported by spool blocks 39 and 40 secured to the base members 41 and 42 of the -gate body 11. Base members 41 and 42 may be formed integral with the gatebody or may comprise separate members (as illustrated) connected to the gate body by bolts 41A land 42A. Both ends of the cylinders `3.3 and 34 are adapted for connection With a source of fluid pressure by means of tubing 43 and 44 so that reversible operationmay be obtained.

A recess 45 is formed in crosshead 17 adjacent the closure member `15 and serves to contain inat-able means according to the invention. In this embodiment of the invention, the iniatable means takes the form of a pressure bag 46 constructed of flexible elastic material, such as rubber or plastic, which is capable of expansion upon internally applied uid pressure. The pressure bag 46 is adapted for connection with a source of fluid pressure by means of a communicating pressure fitting 47. The communicating pressure fitting comprises a hollow bolt which passes through the upper Wall of the pressure bag in sealed relation thereto and through the crosshead 17. The upper end of the bolt 47 is threaded to receive nut 43 which clamps the pressure bag to the crosshead. Tubing 49 connects the pressure fitting 47 with alsource of uid pressure. A drain arrangement 50 similar 1n construction to the pressure fitting is located at the lower wall of the pressure bag 46 and includes a removable pipe plug 51. When the interior of the pressure bag 46 1s connected to a source of fluid pressure by means of tting 47 and tubing 49, the walls of the -bag expand and a portion of its surface bears against closure member 15 to press it against the facing 16 with a force proportionate to the fluid pressure existing in the bag. By thrs means, a tight frictional engagement is produced between the closure member and the facing to prevent leakage when the gate is closed.

In order to control the pressure applied to the inllatable means, a spring-loaded piston valve 52 is mounted on the crosshead 17 for movement therewith. The function of the spring-loaded piston valve is Ito connect the inatable means with a source of uid under high pressure when lthe crosshead is in `a gate closed position and to a source of fluid under reduced pressure for all other posi tions of the crosshead. A suitable valve for this purpose is a Becket Hi Cyclic air valve, model BSL. As seen in FIG. 4, the piston valve 52 is aflxed to the crosshead by mounting bracket 53 and screws 53A and' has an operating member or piston 54 which is biased to an extended position by spring 55. Tubing 49 connected to the iniiatable means is also directly connected to the output 56 of the piston valve. The inputs 57 and 58 of the valve are connected respectively to the source of high fluid pressure and the source of reduced fluid pressure.

Adjustable stop member 59 is located on the base of the gate body 11 and is in the path of movement of the piston 54, so that vertical movement of the crosshead causes the piston to come in contact with the stop member to actuate the valve. The stop member 59 may comprise a bolt 59A threadedly engaging the base member of the gate body and may also include a lock nut 59B. When the valve is in an unoperated position, as when the crosshead is raised, the inatable means is connected by the valve to the source of reduced fluid pressure. As the crosshead is lowered to close the gate, the piston 54 strikes the stop member 59 to operate the valve and connect the inflatable means to the source of high fluid pressure. By this means, a tight frictional engagement is produced between the closure member `and the facing when the gate is closed and a lesser frictional engagement produced for all other positions of the gate, so that a minimum of operating force is needed to open and close the gate.

Referring now to FIG. 5 of the drawing, there is shown a schematic diagram of a fluid pressure operated control system which may be employed to open and close the gate and also to supply the uid pressure applied to the inflatable means. As seen therein, asource-of uid under high pressure is provided at 60 and may, for example, have a Value of 1.00 p .s.i. A control valve 61 has its input 62 connected to the pressure source 60 and4 its outputs 63 and 64 connected respectively to the lower and upper ends of the double-acting pressure cylinders 35 and 36 by means of tubing 65 and 66. An exhaust port 67 is located on the control valve 61 and serves to transiently connect the outputs 63 and 64 to the atmosphere as the valve is shifted from one position to another. A suitable control valve for this use has been -found to be a 4-way Nopack valve which is commercially obtainable. A source of uid under reduced pressure, for example p.s.i., is obtained by means of a conventional pressure reducer 68 which is connected to the high pressure source 60 by tubing 69. The output of the pressure reducer is connected through an indicator 70 of conventional design and tubing 71 to input 58 of the springloaded piston valve 52. The other input 57 of the piston valve is connected to the output 63 of the control valve 61 by means of tubing 72 and 65. When a Beckett Hi Cyclic valve is used for the piston valve 52, the exhaust port usually found thereon is plugged by any suitable means, such as a pipe plug.

In operation, with the control valve in the gate closed position, as indicated by the solid line construction in the draw-ing, the high pressure source 60 is connected to t-he lower ends of the cylinders 33 and 34 by means of tubing 65 and 44. Since the pistons of the doubleacting cylinders 35 and 36 kare xed, the cylinders 33 and 34 will be moved vertically downward to move the crosshead to the closed position. When the crosshead reaches the gate closed position, the spring loaded piston valve 52 will be actuated by contact of piston 54 with stop member 59 and the iniiatable means will be connected to the source of high fluid pressure by means of tubing 49, 72 and 65. At Ithis position, the inflatable means exerts a large .force against the closure member 15, and the gate s effectively sealed against leakage. When the control valve 61 is shifted to a gate open position, as indicated by the dotted line positions of its handle in FIG. 5 of the drawing, the outputs 63 and 64 are transiently connected to the atmosphere by the exhaust port 67, and the lower ends of the cylinders 33 and 34 vented. It will also be noted that since input 57 of the springloaded piston valve is connected to output 63 of the control valve, that the inatable means is also transiently vented by operation of the control valve from the gate closed to the gate open position. With the control valve in the gate open position, the high pressure source is connected to the upper ends of cylinders 33 and 34 by means of tubing 66 and 43, and the crosshead is raised to open the gate. In its initial rising movement the crosshead moves independently of the closure member 15 for a small distance corresponding to the vertical clearance between the ends of the bolts 19 and their sockets 20, and in the course of this lost motion the piston Valve 52 is moved by spring 55 to a position 4at which the piston valve connects the inflatable means to the source of fluid under vreduced pressure by means of tubing 49 and 71. Thus, a lesser frictional engagement is provided between the closure member and facing, and onlya small operating force is needed to raise and lower the crosshead and gate.

If desired, a pair of tube connecting blocks 73 and 74 may be placed on the gate body and crosshead, respectively, to facilitate the tubing connections. As seen in FIG. 4, the tube connecting block 74 is of simple construction, having three passageways 75, 76 and 77 formed therein for connection to tubing 65, 66 and 71. The connecting block 74 is connected to the crosshead by means such as bolts 7S and 79. The construction of tube connecting block 73 may be similar to that of connecting block 74 and will not be further described.

Referring now to FIGS. 6, 7 andv 8 of the drawing, there is shown an alternative embodiment of the invention, wherein a different type of inatable means is ernployed. In describing and illustrating this embodiment of the invention, the same reference characters will be 0 used kfor parts which are similar to those described in connection with the embodiment of FIGS. l to 3.

In this form of the invention, the inflatable means comprises a rigid member forming a cavity and a wall or diaphragm 101 sealing the cavity. The rigid member may be constructed of any suitable material, such as cast metal or plastic, and the diaphragm may be constructed of a ilexible elastic material such as rubber or certain types of plastic. The diaphragm 101 is seated around the periphery of the rigid member and is secured thereto by a retaining frame 102 which is itself secured to the rigid member 100 by screws 103 spaced about the periphery of the frame. By this fmeans, the rigid member is effectively sealed. A communicating pressure fitting 104 which may comprise a threaded tubular member is screwed into a bore 105 located in the upper wall of the rigid member 100. The fitting 104 passes through a bore 106 in the upper portion of the crosshead 17 so that connection may be made to the spring-loaded piston valve 52 by means of tubing 49. A drain 107 may be of similar construction and is located on the lower wall of the rigid member 100.

The rigid member 100 with the retaining frame 102 and diaphragm 101 are located in the recess 45 of the crosshead. Closure member 15 is connected to the rigid member by pins 109 which are pressed into the rigid member and extend into sockets 110 formed in the closure member. The sockets 110 (see FIG. 8) are sufficiently large that a degree of lost motion is provided between the closure member and the rigid member in the direction of the facing extension. Cap screws 108 threadedly engage the crosshead and bear against the retaining frame 102 to maintain a clearance between the inatable means and the crosshead. Adjustment of this clearance may be made by varying the thickness of spacer elements 108A which are located between the heads of cap screws 108 and the crosshead 17. When the inilatable means is connected to a source of fluid pressure by means of tting 104, the diaphragm 101 expands and bears against the crosshead 17 through a bearing plate 111 which is located between the diaphragm and the crosshead. This causes the rigid member to move relative to the crosshead and hence bear against the closure member to produce a tight frictional engagement between the closure member and the facing, thus. preventing leakage from the gate.

The operation of this embodiment of the invention with regard to the control system of FIG. 5 is identical to that of the embodiment disclosed in FIGS. l to 3 and will not be further described herein. This particular construction of the inatable means, however, permits of easier replacement and repair, since it is a simple matter to replace the diaphragm 101 by removing the retaining frame 102 from the rigid member 100.

While preferred embodiments of the invention have been described in detail in accordance with the applicable statutes, this is not to be taken as in any way limiting the invention, but ymerely as being descriptive thereof.

What is claimed is:

l. A loading gate for controlling the ow of material such as mixtures of sugar crystals and syrup from a tank or the like, comprising a gate body providing a passageway terminating in an outlet, a facing on the outlet end of said body presenting a bearing surface extending in a single plane around the outlet and away from the outlet to one side thereof, a closure member formed to cover said outlet and slidable on said facing surface to open. and close said outlet, a crosshead arranged to extend across said outlet, means slidably mounting the ends of said crosshead at opposite sides of said outlet for movement of said crosshead in a path parallel to said plane, said closure member lying between Said crosshead and said facing and being connected with said crosshead for movement therewith by means providing a finite limited freedom of movement of said crosshead relative to said closure member in said path whereby the crosshead travels independently of the closure member for alimited distance beyond the closed position of the closure member, fluid pressure responsive means carried by said crosshead including a wall bearing slidably against said closure member and displaceable transversely thereagainst by fluid pressure to seal said closure member against said facing, and means for supplying a fluid under regulated pressure to said pressure responsive means.

2. A loading gate for controlling the flow of material such as mixtures of sugar crystals and syrup from a tank or the like, comprising a gate body providing a passageway terminating in an outlet, a facing on the outlet end of said body presenting a bearing surface extending in a single plane around the outlet and away from the outlet to one side thereof, a closure member formed to cover said outlet and .slidable on said facing surface to open and close said outlet, a crosshead arranged to extend across said outlet, means slidably mounting the ends of said crosshead at opposite sides of said outlet for movement of said crosshead in a path parallel to said plane, said means including guides iixed to opposite sides of said gate body back of said outlet and rigid members on the ends of said crosshead slidably engaging back sides of said guides so as to move therealong yet prevent movement of said crosshead .transversely to said plane, said closure member lying between said crosshead and said facing and being connected with said crosshead for movement therewith by means providing a finite limited freedom of movement of said crosshead relative to said closure member in said path whereby the `crosshead travels independently of the closure member for a limited distance beyond the closed position of the closure member, .tiuid pressure responsive means carried by said crosshead including a wall bearing slidably against said closure member and displaceable transversely thereagainst by fluid pressure to seal said closure member Vagainst said facing, and means for supplying a fluid under regulated pressure to said pressure responsive means.

3. A loading gate for controlling the liow of material such as mixtures of sugar crystals and syrup from a tank or the like, comprising a gate body providing a passageway terminating in an outlet, a facing on the outlet end of said body presenting a bearing surface extending in a single plane around the outlet and away from the outlet to one side thereof, a closure member formed to cover said outlet and slidable on said facing surface to open and close said outlet, a crosshead arranged to extend across said outlet, means slidably mounting the ends of said crosshead at'opposi'te sides of said outlet for movement of said crosshead in a path parallel to said plane, said closure member lying between said crosshead and said facing and being connected with said crosshead for movement therewith by means providing a limited freedom of movement of said crosshead relative to said closure member in said path, said crosshead being formed with a recess in the side thereof facing said closure member, and fluid pressure responsive means including a flexible elastic pressure bag located in said recess and having an elastic wall bearing slidably against said closure member and displaceable transversely thereagainst by fluid pressure supplied into said bag to seal said closure member against said facing.

4. A loading gate for `controlling the iloW of material such as mixtures of sugar crystals and syrup from a tank or the like, comprising a gate bodyA providing a passageway terminating in an outlet, a facing on the outlet end of said `bodyrpresenting a bearing surface extending in a single plane around the outlet and away from the outlet to one side thereof, a closure member formed to cover said outlet and slidable on said facing surface to open and close said outlet, a cross head arranged to extend across said outlet, means slidably mounting the ends of said crosshead at opposite sides of said outlet for movement of said crosshead in a path parallel to said plane, said closure member lying'between said crosshead and said facing and being connected with said crosshead for movement therewith by means providing a limited freedom of movement of said crosshead relative to said closure member in said path, said crosshead being formed with a recess in the side thereof forming said closure member, and fluid pressure responsive means including a rigid plate member lying in said recess and bearing slidably against said closure member and displaceable transversely thereagainst by fluid pressure to seal said closure member against said facing.

5. A loading gate for controlling the flow of material such as mixtures of sugar crystals and syrup from a tank or the like, comprising .a gate body providing a passageway terminating in an outlet, a facing on the outlet end of said body presenting a bearing surface extending in a single plane around the outlet and away from the outlet to one side thereof, a closure member formed to cover said outlet and slidable on said facing surface to open and close said outlet, a crosshead arranged to extend across said outlet, means slidably mounting the ends of said crosshead at opposite sides of said outlet for movement of said crosshead in a path parallel to said plane, said closure ymember lying between said crosshead and said facing and being connected with `Vsaid crosshead for movement therewith by means providing a limited freedom of movement of said crosshead relative to said closure member in said path, a fluid pressure cylinder carried directly on each end of said crosshead, a fixed piston in each of said cylinders and means for supplying liuid under pressure into said cylinders at either side of said pistons to move sai-d crosshead and said closure member.

6. A loading gate for controlling the iiow of material such as mixtures of sugar crystals and syrup from a tank or the like, comprising 'a gate body providing a passageway terminating in an outlet, a facing on the outlet end of said body presenting a bearing surface extending in a single plane around the outlet and away from the outlet to one side thereof, a closure member formed to cover said outlet and slidable on said facing surface to open and close said outlet, a crosshead arranged to extend across said outilet, means slidably mounting the ends of said crosshead at opposite sides of said outlet for movement of said crosshead in a path parallel to said plane, said closure member lying between sai-d crosshead and said facing and being connected with said crosshead for movement therewith by means providing a limited freedom of movement of said crosshead relative to said closure member in said path, a fluid pressure cylinder carried directly on each end of said crosshead, the two cylinders being located in alignment with said plane, a fixed piston in each of said cylinders, a fixed post supporting each piston, rigid supporting means for said posts iixed to the under side of said gate body, and means for supplying iluid under pressure into said cylinders at either side of said pistons to` move said crosshead and said closure member.

7. A loading ygate for controlling the iiow of material such as mixtures of sugar crystals and syrup from a tank or the like, comprising a gate body providing a passageway terminating in an outlet, a facing on the outlet end yof said body presenting a bearing surface extending in a single plane around the outlet and away from the outlet to one side thereof, a closure member formed to cover said outlet and slidable on said facing surface to open and close said outlet, a crosshead arranged to extend across said outlet, means slidably mounting the ends of said crosshead at opposite sides of said outlet for movement of said crosshead in a path parallel to said plane, said closure member lying between said crosshead and said facing and being connected with said crosshead for movement therewith by means providing a limited freedom of movement of said crosshead relative to said closure member in said path, a uid pressure cylinderheldby each en'd of'said'-crosshead,'the Yends'of said crosshead forming split sleeves releasably clamping said cylinders therein, a fixed piston in each of said cylinders, a fixed post supporting each piston, rigid supporting means for said posts xed to the under side of said gate body, and means for supplying fiuid under pressure into said cylinders at either side of said pistons to move said crosshead and said closure member.

8. A loading gate for controlling the flow of material such as mixtures of sugar crystals and syrup from a tank or the like, comprising a gate body providing a passageway terminating in an outlet, a facing on the outlet end of said body presenting a bearing surface extending in a single plane around the outlet and away from the outlet to one side thereof, a closure member formed to cover said outlet and slidable on said facing surface to open and close said outlet, a crosshead arranged to extend across said outlet, means slidably mounting the ends of said crosshead at opposite sides of said outlet for movement of said crosshead in a path parallel to said plane, said closure member ly-ing between said crosshead and said facing and being connected with said crosshead for movement therewith by means providing a limited freedom of movement of said crosshead relative to said closure member in said path, fluid pressure responsive means carried by said crosshead including a wall bearing slidably against said closure member `and displaceable transversely thereagainst by fluid pressure to seal said closure member against said facing, a fiuid pressure cylinder held by each end of said crosshead, a fixed piston in each of said cylinders, means for supplying fiuid under pressure into said cylinders at either side of said pistons to move said crosshead and said closure member, and means for simultaneously supplying a fluid under regulated pressure to said pressure responsive means.

9. A loading gate for controlling the fiow of material such as mixtures of sugar crystals and syrup from a tank or the like, comprising a gate body providing a passageway terminating in an outlet, a facing on the outlet end of said body presenting a bearing surface extending in a single plane around the outlet and away from the outlet to one side thereof, a closure member formed to cover said outlet and slidable on said facing surface to open and close said outlet, a crosshead arranged to extend across said outlet, means slidably mounting the ends of said crosshead at opposite sides of said outlet for movement of said crosshead in a path parallel to said plane, said closure member lying between said crosshead and said facing and being connected with said crosshead for movement therewith by means providing a limited freedom of movement of said crosshead relative to said closure member in said path, fluid pressure responsive means carried by said crosshead including a Lwall bearing slidably against said closure member and displaceable transversely thereagainst by fiuid pressure to seal said closure member against said facing, and means operative to supply to said pressure responsive means, alternately, a high fluid pressure sufficient to seal said closure member immovably against said facing when said member is in closed position, and a reduced fluid pressure sufiicient to keep said member sealed against said facing as said member is moved to and from open position.

10. A loading gate for controlling the flow of material such as mixtures of sugar crystals and syrup from a tank or the like, comprising a gate body providing a passageway terminating in an outlet, a facing on the outlet end of said body presenting a bearing surface extending in a single plane around the outlet and away from the outlet to one side thereof, a closure member formed to cover said outlet and slidable on said facing surface to open and close said outlet, a crosshead arranged to extend across said outlet, means slidably mounting the ends of said crosshead at opposite sides of said outlet for movement of said crosshead in a path parallel to said plane, said closure member lying between said crosshead and said facing and being connected with said crosshead for movement therewith by means providing a limited freedom of movement of said crosshead relative to said closure member in said path, fluid pressure responsive means carried by said crosshead including a wall bearing slidably against said closure member and displaceable transversely thereagainst by fiuid pressure to seal said closure member against said facing, and means operative to supply to said pressure responsive means, alternately, a high fluid pressure sufiicient to seal saidl closure member immovably against said facing when said member is in closed position, and a reduced fluid pressure sufficient to keep said member sealed against said facing as said member is moved to and from open position, said pressure supply means including means operative to vent the fluid pressure from said pressure responsive means in the transition from supplying said high fiuid pressure to supplying said reduced fiuid pressure.

11. A loading gate for controlling the flow of material such as mixtures of sugar crystals 'and syrup from a tank or the like, comprising a gate body providing a passageway terminating in an outlet, a fac-ing on the outlet end of said body presenting a bearing surface extending in a single plane around the outlet and away from the outlet to one side thereof, a closure member formed to cover said outlet and slidable on said facing surface to open and close said outlet, a crosshead arranged to extend across said outlet, means slidably mounting the ends of said crosshead at opposite sides of said outlet for movement of said crosshead in a path parallel to said plane, said means including guides fixed to opposite sides of said gate body back of said outlet and rigid members on the ends of said crosshead slidably engaging back sides of said guides so as to move therealong yet prevent movement of said crosshead transversely to said plane, said closure member lying between said crosshead and said facing and being connected with said crosshead for movement therewith by means providing a limited freedom of movement of said crosshead relative to said closure member in said path, a fluid pressure cylinder held by each end of said crosshead, a fixed piston in each of said cylinders, a fluidtight chamber carried by said crosshead and having a wall displaceable transversely against said closure member by fluid pressure in said chamber to press said closure member against said facing, a source of high fluid pressure, a source of reduced fluid pressure, control means operative in one position to supply said high pressure into the lower ends of said cylinders and thus move said crosshead in gate closing direction, said control means being movable to a second position to supply said high pressure into the upper ends of said cylinders and thus move said crosshead in gate opening direction, means operated upon movement of said crosshead to gate closed posit-ion to supply said high pressure into said chamber and thus lock said closure member against said facing, means operated in the transition of said control means from said one position to said second position to vent the fluid pressure from the lower ends of said cylinders and from said chamber, and means rendered operative upon movement of said crosshead away from gate closed position to supply said reduced pressure into said chamber to keep said closure member sealed against said facing as said member is moved to and from open position.

References Cited in the filel of this patent UNITED STATES PATENTS 708,990 Bickford Sept. 16, 1902 1,360,805 Sherman Nov. 30, 1920 1,834,870 Rogers Dec. 1, I1931 (Other references on following page) l 1 UNITED STATES PATENTS 2,476,711 Murphy Apr. 29, 1941 640565 Kinzie Dec. 9, 1941 Rufus Aug. 18, 194/2 Hertrich Dec. 28, 1943 5 6,541 Caldwell Oct. 9, 1945 1,114,153

12 Edwards July 19, 1949 Hoppenstand June 2, 1953 FOREIGN PATENTS Great Britain June 2, 1904 France Dec. 12, 1955 

